JP2008101288A - Monofilament for screen gauze, excellent in dimensional stability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monofilament which has excellent weaving stability when processed, is excellent in dimensional stability required for continuous printing performance, and is suitable for obtaining a high mesh high modulus screen gauze. <P>SOLUTION: The polyester monofilament for screen gauze satisfies the followings: the largest point strength of a raw filament before a thermal treatment is 5.0-7.0 cN/dtex; the strength at an elongation of 5% is 2.5-3.7 cN/dtex; the largest point elongation is 20-45%; wet heat shrinkage percent is 2.5-9.0%; the largest point strength of the raw filament after a wet heat treatment after woven is 5.0-6.5 cN/dtex; the strength at an elongation of 15% is 3.0-5.0 cN/dtex; the largest point elongation is 20-40%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyester monofilament suitable for obtaining a high-mesh, high-modulus screen wrinkle that requires high precision, such as mesh fabric for screen printing, particularly for the production of printed wiring boards.

  Monofilaments have been widely used not only in the clothing field but also in the industrial material field. Examples of applications in the latter field of industrial materials in particular include monofilaments as raw yarns for tire cords, ropes, nets, tegus, tarpaulins, tents, screens, paragliders and sailcloths. The physical properties required for this monofilament are becoming strict, and improvements such as adhesion to rubber, fatigue resistance, dyeability, abrasion resistance, and knot strength are being urged. Especially in the recent printing in the electronic circuit field, the degree of integration is increasing, and there is a demand for higher printing density and improved printing as screen screens, that is, high strength, high modulus and high mesh. It is getting stronger. The raw yarn is also required to have high strength, high modulus, and fineness.

  JP-A-2-289120 proposes a specific value for the rupture strength and elongation of a raw yarn before weaving when the screen yarn is designed. However, in the production of screen wrinkles, since the texture adjustment, heat setting, and tensioning processes are performed, the strength and elongation of the yarn changes particularly by wet heat treatment after weaving. Therefore, the physical property values of the raw yarn before weaving are simply specified. However, there was a problem that the dimensional stability at the time of precision printing of the screen 欠 け was lacking.

  Japanese Patent Laid-Open No. 2-277818 discloses that a monofilament for a screen with good dimensional stability can be obtained by setting the strength, the strength at 12.5% elongation, and the dry heat shrinkage within a specific range. Yes. However, there are wet heat processes such as refining and dyeing processes in the screen wrinkle manufacturing process, which does not take into account changes in the physical properties of the yarn due to wet heat shrinkage, etc. and is not satisfactory in fields that require high dimensional stability. It was.

  Japanese Patent Application Laid-Open No. 2005-47020 proposes to set specific values for breaking strength, elongation, and boiling water shrinkage as raw yarn physical properties. This method takes into account the shrinkage in the wet heat process, and although the dimensional stability is improved to some extent, it does not prescribe the physical properties of the yarn before and after shrinkage, so the dimensional stability varies between lots of screen wrinkles. It was subject to equal stability.

JP-A-2-289120 JP-A-2-277818 JP-A-2005-47020

  An object of the present invention is to provide a high-mesh, high-modulus polyester monofilament for screen wrinkles that is excellent in continuous printing performance, particularly dimensional stability.

A high-strength, high-modulus monofilament for screen wrinkles, which satisfies the following A to E: A polyester monofilament for screen wrinkles.
A. Monofilament maximum tensile strength before wet heat treatment of 5.0 to 7.0 cN / dtex, strength at 5% elongation of 2.5 to 3.7 cN / dtex, maximum elongation of 20 to 40%, wet heat The shrinkage rate is 2.5 to 9.0%.
B. The monofilament has a maximum yarn point strength after wet heat treatment of 5.0 to 6.5 cN / dtex, a strength at 15% elongation of 3.0 to 5.0 cN / dtex, and a maximum point elongation of 20 to 45%. thing.
C. The intrinsic viscosity of the polyester is 0.70 to 1.00 dL / g.
D. The single yarn fineness is 4 to 24 dtex.
E. The number of knots is 1.1 or more times the fiber diameter in the monofilament longitudinal direction of 500,000 meters.

  In the screen filament monofilament, by setting the raw yarn properties before weaving, the shrinkage rate, and the raw yarn physical properties after wet heat treatment after weaving to specific values, a screen wrinkle with good dimensional stability in precision printing can be obtained stably.

  A fine filament monofilament of 24 dtex or less is used for a high mesh screen (200 to 500 mesh) suitable for precision printing. The filaments for woven fabrics must have specific properties such as strength and elongation enough to suppress the occurrence of deterioration in weaving properties and the elongation of screen creases during printing (decrease in dimensional stability). In general, the performance is evaluated by the stress (modulus, hereinafter 5% LASE) when the elongation of the raw yarn is 5%. However, in order to obtain a higher degree of dimensional stability, the present inventor The present inventors have found that it is important to consider the influence of raw yarn on the wet heat treatment in the production process of screen wrinkles. (Wet heat treatment means that the screen weave is usually woven with warm water or steam during refining or dyeing) Based on these findings, according to the present invention, the screen The monofilament for use is a high IV polyester polymer of 0.7 to 1.0 dL / g to make a fine filament monofilament with a single yarn fineness of 4 to 24 dtex, and the monofilament has a maximum point strength before wet heat treatment of 5.0 to 7 0.0 cN / dtex, strength at 5% elongation is 2.5 to 3.7 cN / dtex, maximum elongation at 20 to 40%, wet heat shrinkage is 2.5 to 9.0%, and after wet heat treatment By setting the maximum point strength to 5.0 to 6.5 cN / dtex, the strength at 15% elongation to 3.0 to 5.0 cN / dtex, and the maximum point elongation to 20 to 45%, Adjustment and humidity After step elapse of the set and gauze lined, screen mesh having excellent highly dimensional stability. The maximum point strength and elongation mean strength and elongation at the time of cutting in the unloading curve of the raw yarn.

  The polyester used in the present invention needs to have an IV of 0.7 to 1.0 dL / g. If it is out of this range, a high modulus and high strength monofilament cannot be obtained.

Examples of the type of polyester used include aromatic polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), and any of them may be used. Among these, PET is most preferable in terms of operability and cost when performing melt spinning.
In order to obtain a high mesh screen wrinkle, the fineness of the monofilament is preferably 4 to 24 dtex, more preferably 5 to 15 dtex.

  The monofilament of the present invention has a maximum point strength before wet heat treatment of 5.0 to 7.0 cN / dtex, a strength at 5% elongation (abbreviated as 5% LASE) of 2.5 to 3.7 cN / dtex, and a maximum point elongation. The degree is designed to be 20-40% and the wet heat shrinkage is 2.5-9.0%.

A higher 5% LASE is preferable, but if it exceeds 3.7 cN / dtex, it is not preferable because scraping due to wrinkles occurs during weaving and is woven into the woven fabric, resulting in defects. On the other hand, if it is 2.5 cN / dtex or less, the dimensional stability at the time of continuous screen printing is deteriorated, misalignment is likely to occur, and this is a disadvantage of the printed matter.
The wet heat shrinkage rate is preferably in the range of 2.5 to 9.0%, and outside this range, the 15% elongation stress after the wet heat treatment cannot be within a specific range, which is not preferable.

  In the present invention, it is important to improve the dimensional stability of the screen ridge after the wet heat treatment by using the maximum strength of the original yarn after the wet heat treatment and the strength at 15% elongation as an index. It is necessary that the maximum point strength after heat treatment is 5.0 to 6.5 cN / dtex, the strength at 15% elongation is 3.0 to 5.0 cN / dtex, and the maximum point elongation is 20 to 45%. .

When the maximum point strength after the wet heat treatment is 5.0 cN / dtex or less, the screen wrinkle strength is insufficient, and misalignment is likely to occur during continuous screen printing, or the wrinkle separation from the printing material during printing is not good. If it is 6.5 cN / dtex or more, scraping due to wrinkles easily occurs during weaving.
On the other hand, when the maximum point elongation is less than 20%, weaving yarn breaks frequently, resulting in poor handleability and the problem of tearing when the sheet is stretched. When the maximum point elongation is 45% or more, wrinkle elongation occurs and dimensional stability is not good.

Although the specific manufacturing method for obtaining the monofilament of this characteristic is demonstrated, it is not necessarily limited to this.
It can be obtained by melt spinning the above-mentioned intrinsic viscosity polyester by a conventional method and drawing. Although it can be wound up as an undrawn yarn once in the spinning step and used for the drawing step, it is preferable to carry out drawing in direct connection with the spinning step.

  In direct spinning drawing, it is preferable to use several pairs of heated rolls and draw in one or more stages, and finally, the draw ratio is determined so that the strength, elongation, and shrinkage rate fall within a predetermined range. This stretching includes relaxation treatment such as relaxation stretching.

  In this way, the properties of the original yarn before weaving are adjusted, and then subjected to the weaving process, and if necessary, shrinkage is performed through wet heat treatment such as refining, dyeing, etc., and the yarn has a predetermined high elongation after wet heat shrinkage. The screen has a high degree of dimensional stability.

  Nodes generated on the surface of the monofilament are undesirable because they cause yarn breakage and scum during weaving, and it is necessary to prevent them from occurring as much as possible. As the cause of the knot, there are unmelted foreign matters contained in the polymer and deterioration of the polymer itself. About the unmelted foreign material in a polymer, the discharge | emission can be suppressed or disperse | distributed by forming a filtration layer from a pack entrance to a nozzle | cap | die discharge port. About this filtration layer, the opening amount of about 20 to 30% of the monofilament diameter is preferable, and if it is 20% or less, abnormal pressure is applied in the pack, leading to breakage of the parts in the pack and the pack body. If it is 30% or more, unmelted foreign matter, which is the main cause of knot yarn, is contained in the yarn as coarse particles, and the risk of knot generation increases. In addition, with regard to the deterioration of the polymer itself, with regard to polymer feeding, the bending of the pipe is reduced, the time from introduction of the pack to discharge is within 1 minute, and the amount of heat received by the polymer is reduced as much as possible to reduce the risk of occurrence of nodes be able to.

The present invention will be described more specifically with reference to the following examples.
In Examples, intrinsic viscosity, strength, elongation, shrinkage rate during wet heat treatment, strength after wet heat treatment, elongation after wet heat treatment, strength at 15% elongation, evaluation of the number of nodes, evaluation of thread scraping, hysteresis Evaluation was performed according to the following definitions.

Intrinsic viscosity:
Dilution solutions of each concentration (C) in which the sample was dissolved in orthochlorophenol at 35 ° C. were prepared, and C was brought close to 0 from the viscosity (ηr) of these solutions by the following formula.
η = limit (ln (ηr / C))
In addition, each component of the core sheath is equivalent to the base used at the time of yarn production and the residence time in melting, and a base designed so that the core and sheath polymers can be discharged separately has been sufficiently stabilized. Above, the release polymer was sampled and measured.

Strength and elongation:
The strength and elongation of the fiber are the strength and elongation when the sample breaks in accordance with JIS-L1017, measured using a Tensilon manufactured by Orientec Co., Ltd. at a sample length of 25 cm and an elongation rate of 30 cm / min. For 5% ASE, the stress was measured when the sample at the time of the above measurement was stretched by 5%.

Moist heat shrinkage:
5000 m was sampled and placed in a skein state, and placed in a high-pressure, 130 ° C., moist heat atmosphere for 10 minutes while applying a fineness × 0.1 times (g). The yarn after the treatment was naturally dried and the yarn length was measured again. The yarn length after the treatment was divided by the yarn length of 5000 m before the treatment, and the percentage of shrinkage after the wet heat treatment was expressed as a percentage.

Strength after wet heat treatment, elongation, 15% ASE:
The strength and elongation of the fiber after wet heat treatment are the strength and elongation when the yarn after wet heat treatment is measured using a Tensilon made by Orientec Co., Ltd. with a sample length of 25 cm and an elongation rate of 30 cm / min, and the sample is broken. . For 15% ASE, the stress was measured when the sample at the time of the above measurement was stretched by 15%.

Evaluation of the number of clauses:
In front of the dropper installed at the creel outlet of the warping machine, 12 slit guides having a clearance of thread diameter × 1.1 times and a tolerance of ± 2 μm were installed. Threads were passed through the slit guide, and 12 yarns × 8 stages = 96 yarns were warped at a yarn speed of 500 m / min, and each yarn length was 200,000 m. At that time, the number of yarn breaks with the slit guide was regarded as the number of knots, and the number of yarn breaks during warping was measured. Evaluation was performed by converting the detected number of times of yarn breakage into a yarn length of 100,000 m.

Evaluation of thread cutting:
A mesh fabric was woven using 300 warps per inch of weaving width with a slewer type loom at a rotation speed of 250 rpm, and the woven fabric was visually inspected with the inspection machine. At this time, the number of fabric defects in which the mesh pattern that normally appears black was whitened was counted and evaluated.
Less than 5 defects due to thread scraping per woven width 1.5 m × fabric length 30 m were evaluated as ◯, 5 or more and less than 10 as Δ, and 10 or more as X.

Hysteresis evaluation (screen 紗 dimensional stability substitute characteristics):
A load at the time of 7% elongation is applied as an initial load to the raw yarn after the wet heat treatment, and then the load (B) when the 1.5% continuous elongation is further increased 1000 times is compared with the load (A) at the 30th time, C = The value of C obtained by B / A × 100 is 98% or less.

[Example 1]
Polyethylene terephthalate with an intrinsic viscosity of 0.86 dL / g. Melting at a temperature of 294 ° C. The intrinsic viscosity sampled 2 hours after the start of discharge was 0.72 dL / g. While being wound at a spinning speed of 1200 m / min, an unstretched yarn was obtained while attaching an oil agent with an oiling roller. Then, after preheating with a heated hot roller, it is stretched at 3.8 times while being heated at 200 ° C., subjected to a relaxation treatment of 0.04 times, wound up, and a 13 dtex-1fil drawn yarn is drawn. Obtained. The drawn yarn obtained had a strength of 5.8 cN / dtex, an elongation of 28%, a 5% ASE of 3.0 cN / dtex, a wet heat shrinkage of 7.0%, and a strength after boiling water treatment of 5.3 cN / dtex, an elongation of 35. %, 15% LASE was 3.8 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 0 per 300 m. Hysteresis evaluation was (circle). When the finished screen koji was continuously printed, it had little elongation and excellent dimensional stability.

[Comparative Example 1]
In Example 1, relaxation stretching was stopped, 1.2-fold stretching was performed at that portion, and the obtained stretched yarn was adjusted to 13 dtex. The obtained drawn yarn has a strength of 5.4 cN / dtex, an elongation of 22%, a 5% ASE of 3.2 cN / dtex, a wet heat shrinkage of 11.0%, and a strength after boiling water treatment of 4.8 cN / dtex, an elongation of 50. %, 15% LASE was 2.4 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 0 per 300 m, but the hysteresis evaluation was x. When the finished screen was continuously printed, the elongation was large and there was a problem with dimensional stability.

[Example 2]
In Example 1, a drawn yarn was obtained in the same manner as in Example 1 except that the slit heater temperature at the time of drawing was changed from 200 to 230 ° C. The obtained drawn yarn had a strength of 5.7 cN / dtex, an elongation of 26%, a 5% ASE 3.1 cN / dtex, a wet heat shrinkage of 6.5%, and a strength after boiling water treatment of 5.5 cN / dtex, an elongation of 30. %, 15% LASE was 4.5 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 0 per 300 m. Hysteresis evaluation was (circle). When the finished screen koji was continuously printed, it had little elongation and excellent dimensional stability.

[Comparative Example 2]
In Example 1, a drawn yarn was obtained in the same manner as in Example 1 except that the slit heater temperature at the time of drawing was changed from 200 to 150 ° C. The obtained drawn yarn has a strength of 5.3 cN / dtex, an elongation of 26%, a 5% ASE 2.9 cN / dtex, a wet heat shrinkage of 12.0%, a strength after boiling water treatment of 4.5 cN / dtex, and an elongation of 60. %, 15% LASE was 2.8 cN / dtex. The number of node yarn generation of the raw yarn was zero. When this raw yarn was woven with a slewer type loom, the number of fabric defects due to the occurrence of yarn shaving was 0 per 300 m. Hysteresis evaluation was x. When the finished screen was continuously printed, the elongation was large and there was a problem with dimensional stability.
The results of Examples 1-2 and Comparative Examples 1-2 are summarized in Table 1.

  The polyester monofilament of the present invention is suitable for obtaining a high mesh and high modulus screen wrinkles required for high precision such as mesh fabric for screen printing, production of printed wiring board and the like.

Claims (2)

A polyester monofilament for screen wrinkles characterized by satisfying the following A to E:
A. Monofilament maximum tensile strength before wet heat treatment of 5.0 to 7.0 cN / dtex, strength at 5% elongation of 2.5 to 3.7 cN / dtex, maximum elongation of 20 to 40%, wet heat The shrinkage rate is 2.5 to 9.0%.
B. The monofilament has a maximum yarn point strength after wet heat treatment of 5.0 to 6.5 cN / dtex, a strength at 15% elongation of 3.0 to 5.0 cN / dtex, and a maximum point elongation of 20 to 45%. thing.
C. The intrinsic viscosity of the polyester is 0.70 to 1.00 dL / g.
D. The single yarn fineness is 4 to 24 dtex.
E. The number of knots is 1.1 or more times the fiber diameter in the monofilament longitudinal direction of 500,000 meters.   A load at the time of 7% elongation is applied to the original yarn after the wet heat treatment as an initial load, and then the load (B) when the 1.5% continuous elongation is further increased 1000 times is compared with the load (A) at the 30th time, C 2. The monofilament for screen wrinkles according to claim 1, wherein the strength deterioration (C) in the repeated elongation recovery obtained by (A−B) / A × 100 is 0 to 1%.